This invention related generally to hot water heating column furnaces, and in particular to a new and novel, improved combination hot water heat exchanger and stripper furnace for use as a non-corrosive, drinking-water-quality heating system, and to a corresponding method for providing such a source of drinking-water-quality hot water for use, for example, in copper pipe systems.
Direct contact, heating hot water column furnaces are known in the art but generally are incompatible with conventional copper pipe water systems.
When the products of combustion (mostly carbon dioxide and water) produce cabonic acid, thisalone generally will not attack the copper pipes. Likewise any oxygen in the solution will not attack the copper pipes either, except to the extent of providing a thin protective coating of oxide on the pipe. However, if both the carbonic acid and the oxygen are present in the solution, their combined effect can cause extreme corrosion of the copper pipes by oxidation from the oxygen and its removal by carbonic acid, thus removing copper oxide from the system.
Prior art furnace designs appear to ignore this problem, and the subject invention is thereby directed to a direct contact water heater column which is formed into two chambers with the upper chamber being a combined heat exchanger and oxygen stripping chamber and with the lower chamber being a combustion chamber and reservoir for the hot water that is heated in the furnace, the combustion chamber and its heat source likewise being designed to avoid NO.sub.x and SO.sub.2 problems.
Prior art type hot water column heater furnaces using direct or semi-direct flame/water contact, will be described briefly for purposes of a more fuller understanding of the present invention:
(1) The U.S. Pat. No. 3,190,283 which issued on June 22, 1965 to Kingo Miyahara is entitled "Compact Instantaneous Water Heater". This patent discloses a water heater using a central combustion chamber for producing hot gases and utilizes a packing of heat-absorbing material above the combustion chamber. Water is sprinkled over the packing such that the water comes in contact with the heated packing and the hot gases and trickles down to a lower, annularly shaped pick-up trough which directs the water to an outlet pipe. A flue at the top of the heater allows escape of combustion products in the normal manner.
(2) The U.S. Pat. No. 3,826,240, issued July 30, 1974 to Kingo Miyahara is entitled "Direct Contact Water Heater". This patent discloses a device similar in operation to that of the U.S. Pat. No. 3,190,283 and additionally teaches a device that has a water jacket containing some water trickling down which has been deflected by the tapered inner wall of the jacket. The water is made to fall through the combustion chamber after passing through the packing.
(3) The U.S. Pat. No. 884,223, issued Apr. 7, 1908 to A. E. Shipley is entitled "Instantaneous Water Heater". This patent discloses an earlier version of the before mentioned type water heaters and employs a single chamber having an upper heat exchange area containing packing and separated from a lower combustion area by a grid. The sprayed water comes in contact with the hot combustion products as in the above device and collects around the open combustion chamber. The stated purpose of having an inner combustion chamber is to prevent the hot combustion from contacting the heater walls causing heat loss by radiation.
(4) the U.S. Pat. No. 3,648,682 issued Mar. 14, 1972 to Jacques Bougard is entitled "Heater with Combustion Chamber Located Below Fluid Distributing Means". This patent discloses a water heater similar to the above except that the flames are confined within a separate combustion chamber within the column, which chamber is opened only at its bottom, isolating the falling water from direct contact with the flames.
(5) The U.S. Pat. No. 2,759,328, issued Aug. 21, 1956 to C. M. Cockrell is entitled "Pressurized Heater for Producing Hot Process Water in Large Quantities from Scale-Forming Water". This patent teaches another type of direct contact water heater and is provided to show the general state of the art of this type of heater.
None of the before mentioned patents discloses the use of a combination hot water heat exchanger and oxygen stripper furnace to produce a non-corrosive drinking-water-quality heating system.
Thus, it should be understood at the outset that the present invention not only serves as a hot water heater but as an oxygen stripper too, achieving results never heretofore achieved in the hot water heater field producing non-corrosive, drinking-water-quality, heated water.
All of the aforesaid prior art will, it is believed, produce corrosive water, as compared to the non-corrosive, drinking-water-quality achieved in the invention. As is candidly admitted in the Bougard U.S. Pat. No. 3,648,642, "As in all heaters of the above type, the hot liquid is corrosive because of its direct contact with the combustion product which latter contain acid anhydride substances." (Col. 2, lines 28-30). With respect to the heater type of Bougard, it is noted that the Bougard device "relates to the provision of a heater of the type comprising, in a column, a combustion chamber situated below a space equipped with fluid-distributing means, in which space the fluids meet in counter current, the heated liquid descending from one end and the combustion gases rising from the other." (Col. 1, lines 3-8).